body {
  margin: 0 auto;
  background-color: rgba(255, 255, 255, 0.974);
}
#topp {
  position: fixed;
  width: 100%;
  background-color: black;
  display: flex;
  /* flex-direction: row-reverse; */
  justify-content: end;
}
#topp a {
  font-size: 14px;
  padding: 2px 15px;
  text-decoration: none;
  color: rgb(191, 191, 191);
  font-family: "微软雅黑";
}

#topp a:nth-of-type(1):hover {
  background-color: rgba(255, 255, 255, 0.974);
  color: rgb(54, 54, 54);
}
#topp a:nth-of-type(1) span {
  display: inline-block;
  width: 14px;
  height: 14px;
  background-color: red;
  vertical-align: middle;

  margin-right: 3px;
}
#topp a:nth-of-type(2):hover {
  background-color: rgba(255, 255, 255, 0.974);
  color: rgb(54, 54, 54);
}
#topp a:nth-of-type(2) span {
  display: inline-block;
  width: 14px;
  height: 14px;
  background-color: red;
  vertical-align: middle;
  margin-right: 3px;
}
#topp a:nth-of-type(3) {
  margin-right: 65px;
}
#topp a:nth-of-type(3):hover {
  background-color: rgba(255, 255, 255, 0.974);
  color: rgb(54, 54, 54);
}
#topp a:nth-of-type(3) span {
  display: inline-block;
  width: 14px;
  height: 14px;
  background-color: red;
  vertical-align: middle;
  margin-right: 3px;
}
#toppp {
  height: 100px;
  background-color: red;
}

#body_1 {
  margin: 0 auto;
  width: 1920px;
  height: 647px;
  background-image: url(../images/image1.png);
  background-repeat: repeat-x;
}
#body_2 {
  margin: 40px auto;
  width: 1440px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
}
#bottom {
  width: 100%;
  height: 500px;
  background-color: #f2f2f2;
  border: solid 1px black;
}
.item {
  position: relative;
  /* border: solid 2px red; */
  overflow: hidden;
  margin-bottom: 40px;
}

.mask {
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0);
  transition: all 0.7s;
}

.item:hover .mask {
  background-color: rgba(0, 0, 0, 0.5);
}

.item:hover {
  cursor: pointer;
}

.item img {
  position: absolute;
  left: 0;
  top: 0;
  width: 730px;
  transition: all 0.7s;
}

.item:hover img {
  left: -30px;
}

.item .intro {
  width: 500px;
  color: white;
  position: absolute;
  font-weight: 100;
  left: 40px;
  bottom: 0px;
  transition: all 0.7s;
}

.item h3 {
  font-size: 30px;
  margin: 10px 0;
}

.item p {
  opacity: 0;
  transform: translate(0, 50px);
  transition: all 0.7s;
  margin: 0;
}

.item:hover p {
  transform: translate(0, 0);
  opacity: 1;
}

.item:hover .intro {
  bottom: 40px;
}

.big {
  width: 700px;
  height: 700px;
}

.small {
  width: 700px;
  height: 330px;
}
